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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 835 |
| 5 | 98568 |
| 6 | 32181958 |
| 7 | 29251894460 |
| 8 | 71613287309909 |
| 9 | 478060061219665260 |
[1,4,23,835,98568,32181958,29251894460, 71613287309909,478060061219665260] |